Wireless telegraphy.



PATENTED JULY 11, 1905.

w. s. 30%. WIRELESS TELEGRAPHY.

APPLICATION FILED MAY 6 1905.

uventoz Witnesses V 4:4; atkmuyl- Patented July 11, 1905.

PATENT WILLIAM STETSON HOGG, OF WASHINGTON, DISTRICT OF COLUMBIA.

WIRELESS TELEGRAPHYP SPECIFICATION forming part of Letters Patent No.794,459, dated July 11, 1905.

Application filed May 6, 1905' Serial No. 259,153.

To all whom it may concern:

Be it known that I, WILLIAM STETsoN Hoes, lieutenant-commander UnitedStates Navy, residing at Washington, in the District of Columbia, haveinvented certain new and useful Improvements in Wireless Telegraphy; andI do hereby declare the following to be a full, clear, and exactdescription of the same, reference being had to the accompanyingdrawings, forming a part of this specification, and to the letters ofreference marked thereon.

This invention relates to wireless telegra phy, the objects of theinvention being to provide for a more certain and accurate detection ofthe electric or other waves of energy transmitted through the naturalmedia.

I have heretofore used, and disclosed the use, of sensitive material ina detector consisting of one or more contacts of selenited metal.

According to the present invention, I make use of comminutedselenited,or sulfited metals, between electrodes or circuitterminals ofsuch form and character, that the heat efiect of the waves of energy andconsequent thermo-electric-power changes occurring between the manymicrophonic contacts of the dissimilar thermo-electric materials,permits greater or less current-flow in a battery-circuit and thevariations may be readily indicated by a sensitive galvanometer ortelephone.

In order to obtain the maximum effect, the following conditions areimportant:

First, the material inclosed between the electrodes should bemicrophonic with a small current-flow; it should have'either a largeplus or large minus thermo-electrio power; it should be decohering inits nature; and it should be durable so as not to be affected by heatingand atmospheric oxidizing influences.

Secondly, one electrode, preferably that by which the current enters,should be at the opposite end of the thermo-electric scale from thecomminuted included material; it should have a small capacity for heat,in order that its temperature mayquickly change with the oscillatingcurrents, and for this reason may well be a line wire ora pointed wireor conductor; it should be durable and not readily afiected by heat inso far as destructibility is concerned and, should be chemically inertwhen heated by the current as regards the comminuted material contactingtherewith, in order that the thermo-electric power between thedissimilar materials, when heated, may not be decreased by theirbecoming of like thermo nature.

Thirdly, the other electrode should be a good conductor and have a largecapacity for heat, in order that there may be no thermoelectric changeof potential at the points of contact therewith.

I am aware that detectors have been constructed embodying thethermo-electric principle and usually by the contact of dissimilarmetals in the form of fine wire adapted to be heated by the oscillatingcurrents to cause changes in current-flow, but I am not aware of anysuch detectors which embody the principles of the present invention.

To obtain all of the desirable conditions enumerated and secure amaximum thermoelectric-power change, is exceedingly difiicult andconsequently in practice a compromise must be made. Selenium is by farthe most electronegative and bismuth the most positive materials.Selenium is, as pointed out by Branly of a decohering nature when it ismixed with tellurium, both being in the form of a powder. It is,however, of great resistance even when annealed, and could hardly bemade microphonic with any current. Antimony and zinc are crystalline andare also highly negative, and nickel although not negative iscrystalline. In order to overcome the objection to the high resistanceof selenium, and to retain its thermo-electric power, a mixture of thecrystalline metals with selenium is made. This is preferablyaccomplished by heating them together to produce a chemical combination,whereby the resistance of the material is decreased and an effectivemicrophonic material with weak currents is formed, especially, if asmall quantity of copper is incorporated with the mixture before beingheated. A high heat due" to the chemical combination is also important,as in this case, i. a. being compounded at a high temperature,

it forms a very suitable compound, not liable to be affected by any heatto which it will be subject in use.

Next to selenium, certain compounds with sulfur have thermo-electriepower and are more or less conductive, mierophonie and decohering, asfor instance, artificial sulfite of copper has positive thermo-electricpower and stability and the same element sulfur combined with thecrystalline metals has many of the same properties. It 'is believed thattellurium compounds would act in the same manner, but I have notattempted to try every possible combination of the sulfur group with theabove metals, although, it is recognized that the compounds so formedare said to conduct by electrolysis, and in such case, it is probablethat after a long lapse of time and constant use the materials mightlose their cfiiciency. However, this may be, if currents of aniilliampere or less are used, any material loss in efficiency wouldtake a long time and therefore might well be disregarded. The nature ofthe electrolysis may be one of the principal factors in the efficientworking of the material, inasmuch as my experiments and use of thematerial have demonstrated that when it is in contact with a materialwhich when heated with it, combines vith it, as for instance the pointof a steel needle, its decohering cfiiciency is decreased. Withoutattempting to theorize upon the possible formation of gaseous selenium,sulfur or other oxids and the possible changes in the resistance ofthese elements by heat, which changes do no doubt take place, it may bestated simply that the thermo-electric power of the heated contacts ofthe materials seems to be the important factor in causing the changes inthe resistance to current-flow through the circuit.

The metal platinum seems to fulfil all conditions best for the electrodeby which the current enters, as it has a small capacity for heat andconsequently is quickly heated, especially when in the form of a linewire or pointed conductor. [t is indestructible except at the highesttemperatures, is itself microphonic in contact on account of its greatnumber of microscopic protuberances and many irregularities and it has aconsiderable difference of thermo-electric power as compared withselenium. However, aluminium, palladinum and metals of the platinumgroup, and non-metallic materials such as carbon in the form offilaments, can be used, as can also a fine copper wire inasmuch as thelatter, when sulfited, forms an excellent electrode, probably on accountof its great positive thermoelectric power (it and aselenide forming amost powerful thermo-electric couple.) \Vhile the materials lastmentioned may be successfully employed, platinum is preferred because ofits durability.

As to the third condition above referred to, a burnished, hardened steelplug has been found to fulfil all the requirements, namely, largecapacity for heat, no sulfiting or oxidation, little coherence andsufficient conductivity at the points of contact of the comminutedselenited material to produce little heat, microphonic action orthermo-electric power effect, the total thermoelectric power being thatbetween the platinum or sulfitcd copper and the selenited comminutedmaterial with its numerous contacts. Obviously, other metallicelectrodes or a carbon plug could be employed without departing from theinvention.

From the foregoing discussion, the action of the detector and theprobable reasons for its sensitiveness and efficiency will be readilyunderstood, and a general description of its construction and the methodof making the comminuted material will now be given.

In the accompanying drawings, Figure 1 is a sectional view through adetector embodying the present invention. Fig. 2 is a diagrammatic viewof the preferred arrangement of the circuits in which the detector maybe used. Fig. 3 is a similar view of a modified arrangement of thecircuits.

The detector itself may be in form similar to the usual coherers andembody a cylinder A of non-conducting material such as glass or hardrubber. On the ends of the cylinder, metal caps B are cemented orsecured and adapted to make contact with the terminals of abattery-circuit. A steel plug C, is in one end of the cylinder, and atthe other end, the cylinder is provided with a movable plug D of anysuitable metal or material with means for securing to it a fine platinumwire or wires E. The adjustment of the movable plug in or out iscontrolled by a tangent-screw H or other suitable adjusting meanswherebya fine adjustment may be attained. As thus constructed, it ispreferred that the detector be mounted in vertical position and with thecomminuted material resting on the steel plug which latter is thereforeat the bottom. The circuit is completed through the comminuted materialby the adjustment of the platinumwire contact at the upper end.Obviously, the platinum wire may be sealed in glass with its extreme endflush with the glass and the whole attached to the movable plug by asuitable metallic cement, or the plug may be fixed and beveled and theregulation effected by turning the detector on its axis, the detector inthis instance being arranged horizontally. It is also obvious that inaddition to theabove old forms of construction of these parts, any otherwell-known form of coherer or means for regulating the relativepositions of the materials therein may be used, thus the glass tube maybe exhausted of air and the regulation of pressure or contact controlledby ICC IIO

the beveled plug before referred to. Nothing is claimed in the presentcase on the particular mechanical construction of the parts forretaining and adjusting the elements of the detector.

' The following formula for making the selenited comminuted material aresome of the numerous formulae practiced by me in the production of aneflicient material and the same method of procedure may be used for theproduction of the sulfited material, instead of the selenited material.All proportions are by volume. One part of the finest zinc filings aremixed with one part of the finest filings of a five-cent nickel, and twoparts of the finest filings of stick selenium. The mixture is thenplaced on porcelain and heated, as by a spiritlamp, when it is foundthat combination takes place with considerable heat. The residue isground fine in a mortar and is then ready for use. Efficient materialmay also be formed of one part of the finest-copper filings, one part ofthe finest filingflof stick selenium, mixed and heated as before untilcombination takes place and then ground fine in themortar Efiicientmaterial may also be formed of one part of the finest copper filings,one part of the flowers of sulfur mixed, heated and ground fine asbefore.

The detector can be used in any receptive electric circuit in whichthere is included a single cell having a voltage not over 1.3 volts, itbeing desirable toreduce the current-flow to aminimum sufficient tocause a microphonic action. Obviously, the result may be secured byincluding the detector with a shunt resistance in the circuit. Excellentresults have been secured by placing the detector together with thetelephone in one of the arms of a VVheatstone bridge and using a volt ormillivolt meter as a galvanometer as shown, for instance, in Fig. 2 ofthe accompanying drawings where (0 indicates the aerial, I) thedetector, c the telephone, g cl gf fixed resistance-arms of the bridge,f e the variable resistance-arm of the bridge, h the galvanometer, voltor millivolt meter, and 11 the cell or cells of the battery.

In use after the usual balancing the galvanometer is brought to zeroreading when the detector is microphonic, by means of the tangent-screwof the detector and upon the receipt of electric impulses the indicatorof the galvanometer fluctuates and indicates that a message is beingreceived, thus giving notice to the operator who thereupon takes thetelephone and receives the message.

In Fig. 3 of the accompanying drawings, the detector B is shown in thecircuit of the battery I in parallel with the resistance D G, and theaerial A is shown with a well-understood arrangement for tuning,although it will be understood that any known or preferred method oftuning may be employed,

inasmuch as the present invention has nothing to do with this feature ofthe system.

The comminuted material of the detector may contain a comminuted metalnot in chemical combination therewith, thus good results have beenachieved with a comminuted material such as described to which has beenadded a small percentage of comminuted platinum, the quantity ofcomminuted metal or platinum added, however preferably beinginsuificient to cause coherence.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

l. A detector for use in wireless telegraphy embodying an electrode andcomminuted conductive material in contact therewith, said electrodehaving a small capacity for heat and the electrodeand comminutedmaterial being of widely-different thermo-electric power.

2. A detector for use in wireless telegraphy embodying a comminutedmicrophonic material, andelectrodes between which the material isincluded, one of said electrodes having a small capacity for heat andthe other a large capacity for heat.

3. A detector for use in wireless telegraphy embodying a contact ofconductive material and a comminuted microphonic conductive material inconductive relation thereto, said contact and comminuted material beingof widely-different thermo-electric power.

4:. A detector for use in wireless telegraphy embodying a contact ofelectropositive conductive material and a microphonic conductivematerial in contact therewith composed of a metal combined with anelectronegative element.

5. A detector for use in wireless telegraphy embodying a contact ofconductive material and a comminuted microphonic conductive material incontact therwith, said contact and comminuted material being the oneelectropositive and the other electronegative.

6. A detector for use in wireless telegraphy embodying a contact of verysmall cross-sectional area and having small capacity for heat and acomminuted microphonic conductive material in conductive relationtherewith, said contact and comminuted material being the oneelectropositive and the other electronegative.

7. A detector for use in wireless telegraphy embodying a contact of verysmall cross-sectional area and acomminuted material in conductiverelation thereto formed of a metal combined with selenium.

8. A detector for use in wireless telegraphy embodying comminutedselenited conductive material included between electrodes one of whichhas a small capacity for heat and the other a large capacity for heat.

9. In wireless telegraphy the combination at the receiving-station, of acircuit arrange- IIO ment embodying a \Vheatstone bridge, a detector andtelephone in one arm of said bridge and balanced by thevariable-resistance arm and a circuit from the aerial including thedetector.

1(). In Wireless telegraphy a receiving-station equipment embodying a Vlheatstone bridge, an adjustable detector and a telephone in one arm ofsaid bridge and balanced by the 'ariablea'esistance arm and a circuitfrom the aerial including the detector. I

11. A detector for use in Wireless telegraphy embodying a comminutedmaterial formed of chemically-combined metal and electronegativematerial.

12. A detector for use in wireless telegraphy embodying acomminutedmaterial formed of chemically-combined metal and selenium.

13. A detector for use in Wireless telegraphy, embodyingacomminutedmaterial formed by 20 a mechanical mixture of acomminuted metal and acomminuted metal chemically combined with an electronegative material.

14. A detector for use in Wireless telegraphy embodying a comminutedmaterial formed of 5 comminuted selenide of a metal mechanically mixedwith comminuted platinum.

WILLIAM STETSON HOGG.

Vitnesses:

THOMAS DURANT, ALEXANDER S. STEWART.

